SIMULIID/E: BLACK FLIES. 



when looking for better food or when about to pupate. 

 The larvae often spin webs and some, at least, pupate in a 

 dense, spun cocoon. Luminous larvae have been described 

 but their light was probably borrowed from the fungi. 



The name March Flies is misleading, as adults rarely 

 appear that early. Some are common about fruit-tree 

 blossoms. The larvae feed on excrement, decaying roots, 

 and logs. The white-winged, rather long-legged, clumsy 

 fly which frequently occurs in large numbers in meadows 

 and is sometimes seen on windows is Bibio albipennis 

 (Plate LXV). 



SIMULIID.E 



Those who know the Black Flies of the North woods, or 

 the Buffalo Gnats and Turkey Gnats of other sections, 

 know some adult Simulids: stout, hump-backed, short- 

 legged biting pests with very interesting larvae. See 

 Plate LXIII. The larvae are black and sit, in colonies, 

 on their tails on rocks, sticks, and leaves in shallow, swift- 

 flowing water. They cling by means of sucker-like hind 

 legs and they also have a front pair, which they use when 

 crawling. Miall's Aquatic Insects is a model of scientific 

 accuracy and charming diction. He says: "If seriously 

 alarmed, the larva lets go, and immediately disappears 

 from sight. But by watching the place attentively, we 

 shall before long see the larva working its way back, and in 

 a minute or two it will be found attached to the very same 

 leaf from which it started, or to some other leaf, equally 

 convenient, which it happens to fall in with. I found the 

 difficulties of observation in fast-flowing water crowded 

 with leaves very great, until at last it occurred to me to push 

 a white plate in among the leaves. Then the dark-coloured 

 larvae became perfectly evident on the white ground, 

 and I was able to see exactly how they managed. When 

 disturbed by the plate, some of them let go, and drift a 

 few inches away. They are not very easily frightened, 

 and most of them remain holding on by their sucker. 

 Those which quit the leaf remain stationary in the torrent 

 or nearly so, and on close observation a thread, or perhaps 



243 



